A record number of museum passes were sold in Hong Kong last year, amid a boom in museum-going fuelled by grand exhibitions of rare artefacts and relics brought to the city to mark the 20th anniversary of its return to Chinese rule.

The 2017 sales reversed a recent trend of lean sales for the annual tickets, but also left government museum advisers scratching their heads over how to sustain the success now what the landmark event is over.

About 315,700 museum passes were sold in the year, an average of about 865 every day, according to the Leisure and Cultural Services Department, more than trebling the figure for 2016.

In 2015, 115,300 were sold, down from 165,700 in 2014.

Admission to permanent exhibitions at the Museum of History, Heritage Museum, Museum of Art, Museum of Coastal Defence, and Dr Sun Yat-sen Museum is free. But a year-long museum pass, costing HK$50 for individuals or HK$100 for a family, gives holders free entry, without queuing for tickets and as many times as they wish to the department’s 14 public museums.

Officials attributed the record sales to the strong response to major exhibitions marking the 20th anniversary of the handover.

Among the more than 1,200 local celebratory events, two museum shows alone attracted more than 1.2 million visitors. The first was a four-month exhibition on ancient Egypt which featured mummies and attracted more than 850,000 visitors to the Science Museum. That was roughly equal to 70 per cent of the museum’s entire attendance for 2016.

“Apart from the mass market, we also need to look after the serious visitors or, if you like, quality viewers, for example, researchers, or teachers,” Wong said.

“For example, we may issue a new class of museum pass, be it called “diamond pass” or “gold pass”, for these quality viewers. And we may reserve some time slots exclusively for them to view the exhibits. We may also organise some seminars for them to discuss with experts or the curator of the exhibition.”